Yu Ji-hyuk had no connections with Ji-won in her previous life, but he is gradually becoming involved in her current life. Su-min invites Ji-won to a school reunion to resurrect the shameful memories of when she was ostracized in high school. Ji-won sees through Su-min's intentions, and with the help of her colleagues, she undergoes a transformation.

Ji-won attends an event with Ji-hyeok and meets someone who will be a future topic of discussion. Ji-hyuk becomes concerned as he observes Ji-won's transformation. After a heated encounter at the high school reunion, Su-min becomes even more obsessed with Ji-won. Meanwhile, as Ji-won tries to provoke Su-min with Min-hwan, she unexpectedly discovers a secret about Ji-hyuk during a work errand.

Ji-hyuk reminisces about his first encounter with Ji-won eight years ago. His sole purpose in coming back is now Ji-won. Su-min manipulates Mr. Kim to steal Ji-won's proposal, while Ji-hyuk tries to assist Ji-won. However, due to misunderstandings stemming from his relationship with Hui-yeon, Ji-won ends up getting angry at Ji-hyuk instead.

Ji-hyuk confesses his feelings to Ji-won, but she has no time to contemplate her own emotions for him. As Ji-won attempts to overcome her destiny and confront forces opposing the original direction of her fate, her name is ultimately omitted from the proposal. Ji-hyuk empowers Ji-won to take a stand and fight, while Ji-won recalls a future known only to her.

The two have discovered that they both traveled back in time! While Ji-won is thrilled to find a comrade, Ji-hyuk starts to avoid her. He suffers alone after learning of the cruel laws of time travel too late. Meanwhile, Ji-won goes on a picnic with Su-min and Min-hwan, managing to leave the two behind. On her way back, she runs into Ji-hyuk, who appears to have sorted out his thoughts.

During the company's autumn workshop, Ji-won and Su-min engage in a fierce battle of wits. It's the first time they confront each other so sincerely. Su-min becomes angry and attempts to cross the line to hurt Ji-won. Eventually, an incident occurs at a supermarket tasting event involving Min-hwan.

With Ji-hyuk's help, Min-hwan proposes to Ji-won. Ji-won spreads rumors at work to start a buzz. Su-min is upset and intentionally tries to turn Min-hwan's mother and Ji-won into enemies to ruin the engagement dinner. However, the night of the dinner arrives, and it's the day Ji-won has been waiting for.

Ji-won ruins the engagement dinner, leaving Min-hwan utterly embarrassed. Employees soon gossip that Ji-won and Min-hwan's engagement has been called off, and he's been cheating with Su-min. Su-min tries to cover it up, but because of her lies, the supermarket incident resurfaces. She's now caught in a crisis and ends up dropping the bomb.

They finally kiss. Ji-won is going full power towards him, while he continually tries to hit the brakes. Eventually, he ends up opening up to Ji-won. On the other hand, Su-min and Min-hwan speed up the wedding due to an unexpected pregnancy, and Ji-won shows up with Ji-hyuk as her date, aiming to outshine the bride.

Ji-hyuk's fiancée, Yu-ra, makes an appearance and creates a rift between Ji-hyuk and Ji-won. Moreover, Ji-won is surprised to hear about Ju-ran's stomach cancer. She is shocked to realize that her fate wasn't passed on to Su-min. Meanwhile, Su-min and Min-hwan, spending their newlywed days discontentedly, acquire information about Ji-hyuk that enrages them.

After an accident that was intended to harm Ji-won, Ji-hyuk gets injured instead and falls into a coma. Ji-won is scared that Ji-hyuk may never wake up. With everyone involved in the accident busy covering their tracks, Ji-won learns the truth behind the accident and seeks out Su-min to confront her memories from a distant past.

Ji-hyuk regains consciousness and quietly trails the person involved in the accident that Yu-ra is trying to conceal. Meanwhile, Ji-won realizes that, in order to pass on her fate to Su-min, she must get Min-hwan to have an affair. Ji-won decides to become Min-hwan's secret lover, pretends to break up with Ji-hyuk, and approaches Min-hwan once more.

Su-min meets Yu-ra and presents compelling evidence, prompting Yu-ra to start finding a way to resolve the situation once and for all. Ji-won and Ji-hyuk initiate their final operations toward Min-hwan and Su-min, finally bringing about the night of destiny!

With Su-min's disappearance after Min-hwan's death, the fate intertwined with Ji-won finally dissolves. Ji-won receives a formal invitation to Chairman Yu Han-il's home and starts planning her future with Ji-hyuk. Just as they are about to attain their happiness, Su-min reappears to conclude the long-forged tragic fate.